Study On Modification Of Sulfide Photocatalyst And High-efficiency Hydrogen Production

Photocatalytic technology uses solar energy to split water into storable hydrogen.Metal sulfides not only have a narrow band gap that responding to visible light,but also the conductivity,high reaction activity,and environmentally friendly.However,there is highly electron-hole to composite efficiency.In order to break through the bottleneck,this paper first explores the raw material ratio and solvent and then constructs ZnIn₂S₄/Ni S heterojunction.The specific content is as follows:（1）Use solvothermal method to synthesize ZnIn₂S₄ semiconductor,use deionized water:absolute ethanol=1:1 as solvent,fix the stoichiometric ratio of zinc source and indium source,increase the input of thioacetamide to synthesize ZnIn₂S₄ semiconductor.After characterization,it was found that the crystallinity and morphology of ZnIn₂S₄ changed significantly with the increase of thioacetamide input,and the double excess thioacetamide was the most obvious.In addition,the light absorption range has been significantly broadened,moreover,the bottom of the conduction band change to more negative,so it has a stronger reducing ability,and its photocatalytic hydrogen production rate is greatly increased to 11.55mmol·g^-1·h^-1.（2）After selecting the appropriate amount of sulfur source input,ZnIn₂S₄ semiconductor is synthesized by solvothermal method with solvents of different proportions.Through comparison,it is found that due to the different physical properties such as polarity of deionized water and absolute ethanol,the synthesized ZnIn₂S₄ has obvious crystallinity,microscopic morphology,specific surface area,absorbance and photocatalytic hydrogen production activity.Among them,the mixed solvent system has the best hydrogen production activity and good stability.The ZnIn₂S₄ synthesized with other solvents also has similar photocatalytic hydrogen production activity two hours before the photocatalysis,but the activity is sharply reduced or even inactivated due to serious photocorrosion.（3）In order to alleviate the photo-corrosion of ZnIn₂S₄,Ni S was designed to be deposited on the surface of ZnIn₂S₄ nanosheets.Through characterization,it is found that the synthesized ZnIn₂S₄/Ni S is more stable than pure ZnIn₂S₄.The reason is that the band gap position of Ni S is close to the valence band of ZnIn₂S₄.Therefore,under the action of the built-in electric field,the holes generated in the valence band of ZnIn₂S₄ migrate to Ni S prevents the oxidation of sulfur on by holes,thereby significantly improving the stability...